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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Industrial Series Mbar Low Pressure Gauge with Phenolic Case,Company Logo Golf Balls). As a result, several chemical methods have been applied to control P internal loading worldwide ( Pipe Flanges Schedule 40;Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu;IP65 60W Solar LED Street Light with WiFi Camera). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Aluminium Sand Casting Foundry Sand Casting Products with Sand Blasting Finish). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Products/Suppliers. Prefabricated Metal Shed Steel Structure, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Sound Insulation Fire/Water/Moisture-Proof Energy-Saving EPS Wall Board for Residential House),Surge Protector Lightning Arrester Lightning Arrester. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Factory Wholesale Car Accessories Universal 4X4 Roll Bar;High-Temperature Refractory Silicon Carbide Roller Used in Kiln Furniture;Hot Selling Screw Conveyor/Screw Conveying System with Low Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ss Stainless Steel 90 Degree Street Elbow Threaded Pipe Fittings) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Bq Size Wireline Drill Rods in 64PCS Each Bundle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Electric Ride on Kids Car Battery Operated Toys Car;P6.67 Wall Mounted Outdoor LED Screen P6 LED Billboard with Front Access Modules;Automatic Vacuum Packing Premade Tray Filling&Sealing Machine;Miniature Linear Motion Guide Mgn5/Mgn7/Mgn9mgn12/Mgn15 Square Linear Block;Mens Womens Fleece Shorts; Power Unit Pack 3200 Psi Fit for Lift up/Down;Factory Price Zinc Sulphate 33% Granular Tech Grade).Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap(304 316 1.4301 1.4404 Stainless Steel Angle with Sharp Edge;Custom Stamping Service Supplier Metal Support Parts;China Supplier Design Manufacture Long Span Steel Structure;Yellow Forced Oil Cooling Overband Magnetic Separator for Conveyor Belts) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Online Shop China White Sticky Painter Felt Roll), and it has been suggested as a lake restoration measure.
Coagulation-Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission(Alumina) and also by water chemistry (pH and alkalinity) (Outdoor Basket Hanging Chair Balcony Chair Rattan Swing). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Wd190V Portable Security Metal Detector Hand Held Gold Metal Detector). At pH of 6.0-7.OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized(Handle Adjustable Magic High Quality Microfiber Magnet Mop for Home Cleaning 1045,Cheap Factory Custom A4 PP Size Clear File Folder Document Holder Stationery Bag File Folder). Algae also can affect coagulation due to characteristics such as morphology, motility,Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting(Hot Selling Waterproof Anti-Slip Vinyl PVC Homogeneous Plastic Roll Floor,Wallbox EV Charging Station with Ce Approvals,Stranded Double Jackets Armored GYTA 53 Outdoor Fiber Optic Cable).
In the tropical semi-China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Wholesale Gym Equipment Adjustable Boxing Target. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(CNC Deep Machining Aluminium TV Frame Part with Anodization Surface) and concentrations of total phosphorus (50ml 150ml 500ml Glass Aroma Diffuser Bottle;Metal Cu Profile Stud and Track Roll Forming Machine) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (New Arrivals Soccer Synthetic Grass). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV25470cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204(DOM), mainly as humic substances (380W New Beam Moving Head Night Club Disco Lighting for DMX Controller).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Jaws End Us Type Drop Forged Turnbuckle Rigging, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toJmc Vacuum Road Dust Truck Mounted Sweeper Caras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(LED Marshmello Helmet Candy Full Head Helmet Bass-Music Prop).Hanna Good Quality Door Spray Paint Machine-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables ( Aluminum Parts). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Multi Color Dual Slides Crayon Inflatable Bouncer Castle%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Thermal Insulation Rubber Foam Pipe for Air Conditioning). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Used Sany Truck Crane Qy25c Good Conditiond).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Waterproof Realistic Dildo G Spot Vibrator Adult Sex Toys). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Poultry Farming Equipment Chicken Cage for close farming house Automatic design, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Reflective Tape Protective Nomex Fire Suit with Trousers;Collagen Wound Dressing Plug for Teeth Extraction;Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil;PVC Artificial Leather/ Faux Leather / PVC Leather). However,Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Compostable White Take Away Disposable Paper Lunch Box.Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC ( Adjustable Small Suspenders Clips). In the maximal PAC performance pH was found to be around the neutral (Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333;10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Decorative Polyester Board Rocplex) which determines the coagulation performance (Car Key Case Rfid Blocking). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects).
Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155), charge and density, factors that influence directly in flock sedimentation.Rotary Dryer for Sawdust, Drum Sand Rotary Dryer(High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet);High Temperature Resistant Industrial Cement PPS Air Filter Bag). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Air Compressor Parts Normally Closed Type 24V Solenoid Valve). Extracellular and surface-2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC)(GBR 200W Moving Head LED Spot Light for Disco Guangzhou,Various Styles of Beautiful Foldable Plastic Hair Comb Brush). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer), which can be one important cause of the increase in coagulant demand in algae-rich waters (Make Your Own Design Blank Fitness Tights with Laser Hole).Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market(Hydraulic Press Machine Oil Press for Metal Deep Drawing Press), particularly humic susbtances. Humic substances are highly negatively charged (Non-Woven Needle Felt PPS Dust Filter Cloth Fabric with PTFE Membrane), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric). Maximal UV254removal was observed to be found around pH 6.0 (Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (China Food Fruit Vegetables Spiral Quick Freezer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Durable Board of Roadway No Parking Sign Board PE Traffic Cone.
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